Method for refining metals



Nov. 1o, 1936'.

G. H. CLAMER 2,060,177

METHOD FOR REFINING METALS Filed Nov. 26, 1935 W Y-555 5 l INVENToR. J/MM, m4 Y n (7a/04M H. Z4/wif BW TM ATTORNEY Patented Nov. 10, 1936 vUNITED STATES PATENT OFFICE METHOD FOR REFINING METALS Application November 26, 1935, Serial No. 51,565

11 Claims.

This invention deals with a method for refining metals, particularly cast iron, and has for its purpose the provision of means for causing the liquid metal to gyrate or rotate about a ver- 6 tical axis in an intermediate hearth or ladle before going to the molds.

Two figures are used to illustrate a preferred form of the apparatus used to carry out the process.

Figure 1 is a diagrammatic, sectional elevation view of a portion of an open hearth or blast furnace containing a charge of molten metal and a spout for discharging said metal into a forehearth.

15 Figure 2 is a plan view of the equipment shown in Figure 1 with arrows representing the whirlpool motion of the metal as it is received from the tangentially arranged pouring spout from the melting furnace. 'I'he point A represents :o the point at which the metal reaches the ladle charge and also the preferred point for making slag or alloy additions. The vent B represents one method for drawing the slag off of the concave surface of the metal in the ladle.

It has previously been shown that metal, and cast iron in particular, is improved when subjected in the liquid state to gyration. Most of the original work on this subject is due to Girardet and results are adequately described in l his French Patents 630,163 and 670,453 and in the Bul. de lAssociation Technique de Fonderies,

October 1929, pp. 395-398 and subsequent papers. The references describe the gyratory movement, means to accomplish it; the favor- $5 able action it exercises in alloys, particularly cast irons; and the intimate mixing which is accomplished with the metals or alloys and additions.

This application describes the treatment of large quantities of metal directly from-an open 40 hearth or blast furnace by the gyratory method, using the force of the metal stream to impart the motion to the metal as it enters the ladle or forehearth.

Previous work in this field has been done with 45 relatively small charges of metals. It has been the practice, for example, to tap from a cupola furnace into a ladle or fore-hearth and to givesaid receptacle a motion, by mechanical means,

which in turn causes the metal to take on the 50 gyratory motion. The charges thus far treated have been batch lots, and the methods proposed have not lent themselves to continuous operation.

Besides the mechanical method of gyrating 65 metals it has been proposed to obtain the same effect by electrical means. Coils comprising a motor field are placed around the periphery of a cylindrical ladle of molten metal and the eld causes the metal to rotate in the pot.

In both methods referred to the metal takes 5 on a rotating motion. 'Ihe container remains relatively stationary. In the first instance the parts of the container describe small horizontal circles but the container itself is prevented from turning by guide systems. In the second method the container is stationary and all movement is effected electrically through its refractory walls. The metal which rotates or gyrates travels fastest at the ladle Walls and successive cylindrical layers between the surface and axis travel at lower speeds, the speed at the center being zero. Because of the friction between these successive layers the metal particles, additions, and inclusions tend to wipe or roll against each other and are forced toward the center of the bath where the turbulence is less vigorous and where they rise to the surface. This action takes place very quickly, approximating only the time necessary to fill the ladle, and produces a decidedly favorable reaction in the metal thus treated.

' Applicant has found that he can obtain the same desirable effect and on a large scale by directing the force of a molten metal stream from an open hearth or blast furnace tangentially into a ladle to cause the desired rotating effect. The process lends itself to either batch or continuous operation and requires no special mechanical or electrical stirring means. In addition to its simplicity it offers, in its preferred form, an excellent method for slag treatment of the molten charge.

In applicants method the pouring spout from the blast furnace or open hearth is directed toward the center bottom of the receiving or treating ladle as in usual practice. When sufficient metal has accumulated to break the force of the stream, the spout is turned to a tangential position so that the metal stream will strike the surface of the ladle charge near the circumferential edge and impart a rotation to the metal in the ladle such as in a whirlpool in the bend of a fast flowing river. This causes the metal to rotate about a vertical axis as previously described.

As the ladle is lled a reactive slag or additions, preferably pre-melted, can be poured in at the point where the metal stream strikes the surface. Any slags or additions thus added are carried down into the metal with the stream and are carried around in the bath with the gyrating metal. 'I'he slag being lighter than the metal mixes with it to perform its function and is quickly forced to the center of the bath where it rises to the surface.

If the charge is being treated in batch lots the slag is skimmed off and the ladle is removed for pouring. The stream of metal from the blast or open hearth furnace is diverted or plugged with a mud gun.

If it is desired to treat the full charge from the furnace, or to work continuously, the same general procedure is followed. It is better practise, however, to draw the metal from the receiving ladle by a bottom tap or by a spout opening into the bottom of the ladle. If a slag is used, depending upon its thickness or the depth of the metal at the mid top surface below the circumferential top surface, it is drawn off, after performing its function, by a side spout or a tube opening out of the bottom. A ladle such as described would preferably be of a size to hold ten tons or more of the liquid metal, although smaller or larger ladies are also effective.

It is not essential that the stream from the main furnace enter the receiving ladle by an overhead spout, but because of simplicity and the slagging action thus afforded it is preferred. The entry can be made at or near the bottom of the ladle or at any point between the bottom and the top, so long as the stream is made to flow tangentially with respect to the circumferential surface of the ladle charge. If the stream does enter the ladle below the metal surface, it is preferred to tap the metal from the top of the ladle. The cutting action of the incoming stream of metal generally -requires that it be so located as to preserve the ladle lining, and this is difficult with an entry other than at the top.

Applicant does not claim slag treatment specifically except in conjunction with the general process of stirring the ladle charge and he does not limit himself to any special slag or slag treatment. He has described the advantage of using a pre-melted slag and has suggested what he considers the best method of applying it to the charge proper.

In view of applicants disclosure it is desired to protect by United States Letters Patent that which is claimed:

1. The method of refining a metal which comprises rotating it about a vertical axis in a container and using the force of a molten metal stream from another receptacle directed into the metal obliquely and substantially tangent to the surface boundary to effect such rotation.

2. The method of refining a metal in a container which comprises tapping said metal from another receptacle and directing the fiow from said receptacle against the surface of metal in said container with a horizontal angle and away from the axis of said container to impart by its force a rotation of the metal in the container.

3. 'I'he method of refining a metal in a ladle which comprises tapping said metal from a melting furnace and directing the flow from said furnace against thesurface of metal in said ladle with a horizontal angle and away from the axis of said ladle to impart by its force a rotation of the metal in the ladle.

4. The method of refining a metal in a ladle which comprises tapping said metal from a melting furnace and directing the fiow from said furnace into said ladle away from its axis and substantially tangent to the inside wall of said ladle to impart by its force a rotation of the metal in the ladle.

5. 'I'he method of refining cast iron which comprises rotating it about a vertical axis in a container and using the force of a stream of liquid cast iron from a blast furnace directed into the metal obliquely and substantially tangent to the surface boundary to effect such rotation.

6. The method of refining a metal which comprises rotating it about a vertical axis in a container, using the force of a molten metal stream from another receptacle directed into the metal obliquely and substantially tangent to the surface boundary to effect such rotation, admitting metal to said container at one point and removing metal from said container simultaneously at another point.

7. The method of refining a metal which comprises rotating it about a vertical axis in a container, using the force of a molten metal stream from another receptacle directed into the metal obliquely and substantially tangent to the surface boundary to effect such rotation, admitting metal to said container at the top and removing metal from said container simultaneously at the bottom.

8. The method of refining a metal which comprises rotating it about a vertical axis in a container, using the force of a molten metal stream from another receptacle directed into the metal obliquely and substantially tangent to the surface boundary to effect such rotation and feeding a reactive slag into said container while the metal is rotating.

9. The method of refining a metal which comprises rotating it about a vertical axis in a container, using the force of a molten metal stream from another receptacle directed into the metal obliquely and substantially tangent to the surface boundary to effect such rotation, feeding a reactive slag into said container simultaneously with and at substantially the same point that the metal enters.

10. 'I'he method of refining a metal which comprises rotating it about a vertical axis in a container, using the force of a molten metal stream from another receptacle directed into the metal obliquely and substantially tangent to the surface boundary to effect such rotation, feeding metal and a reactive slag into said container at one point and simultaneously removing metal and spent slag from the container at different points.

11. The method of refining a metal which comprises rotating it about a vertical axis in a container, using the force of a metal stream from another receptacle directed into the metal obliquely and substantially tangent to the surface boundary to effect such rotation, and feeding a liquid reactive slag into said container while the metal is rotating.

GUILLIAM HENRY CLAMER. 

